Going mad trying to get this bike working.

[jackstringer]

I broke it a few years ago so it stayed unloved in the shed for a while. During COVID I got around to rebuilding it. Put it back together and then I ran into some issues, the wiring loom was cracked and shorting out all the time. So I have changed a few things.

I removed the old Lucas rectifier and fitted a modern full bridge rectifier a KPBC3510 which I bought at an autojumble. I also swapped out the battery for a Cyclon Battery.

I'm getting running issues that make me think it is the electrics. The bike has a feature that allows the bike to be started using Emergency Start which starts the bike without connecting to the battery etc but once started if you give the bike any amount of throttle it starts to pop and bang a lot. The issue I have currently is the bike starts (sometimes) then it will tick over happily but as soon as I go to ride off it stutters and pops and bangs just like it is in emergency mode and after a few attempts to go somewhere it really becomes hard to start.

The bike is just 6V electrics which are really really basic. What I am wondering is whether the rectifier is failing as it got hot a few times, not being helped by a battery that charges via a constant voltage type system. There is no regulator for 6V just a magnet spinning around a coil (stator) to generate the single-phase power. I have checked the timing, replaced the condenser and the coil etc. so covered a lot of the basics.

I have fitted a new carb and that is set up ok and is clean. Sparkplugs are new, but the same with old spares though I would say the spark is a little weak. I went through the bike again yesterday and I did find the pushrods were a little tight but that may have been the cause of the bike losing power (it would die as if it was seizing) on longer test rides before the recent pop bang started which at times would mean the bike would stop within 25 meters of home, yesterday I managed 500m but not without having to coax it, too many revs and the bike would start to falter eventually it stopped and I had to freewheel home.

For the moment I have ordered a gel battery as I am not sure if the bike likes the Cyclone as I know my battery chargers seem to get a little confused with it at times. I have also ordered a different rectifier to see if that has issues as well, I wondered if it overheated and is a little broken.

1961 G3LS btw.

[SPRIDDLER]

I broke it a few years ago so it stayed unloved in the shed for a while............the wiring loom was cracked and shorting out all the time. So I have changed a few things.

The bike has a feature that allows the bike to be started using Emergency Start .. The issue I have .. it will tick over happily but as soon as I go to ride off it stutters and pops and bangs just like it is in emergency mode

You know your way around old bikes and I've not had a bike with coil ignition or an emergency start function. It's a daft thought I know but picking the bones out of your post, which I gather refers to misfiring when the switch is in the normal running position (i.e. not the 'Emergency' position), could it be that when you 'made a few changes to the wiring loom' you have inadvertently wired the switch with the Emergency start wiring to the switch 'normal' running contacts?

[jackstringer]

Sorry Spriddler,
Yes it seems to do the pop bang rough running thing when in normal mode. I have checked and the switch is wired up ok. I have managed a few trips to work and back with it stopping halfway as the engine loses power and stops, this is why I fitted a new carb, and I think was I thought was seizing could possibly been just the pushrods being a little tight.

Problem I have is my dad borrowed it, rode it to his work and it died halfway up the a very steep hill. He and his coworkers set about getting it running but they left the ignition on so when I got the bike home it had been left on for a week. Since then I have had the pop bangs. I did charge the battery up and it seems ok as it has charge to light up the lights and meep the horn.

[Groily]

Sounds to me as if the problem might be points / condenser related rather than a charging or fuel fault. The symptoms are certainly suspiciously dodgy condenser-like.
If the ignition was left on for week, points shut, then the points might also be a bit scarred.
A problem in this area would explain poor running in the normal ignition position quite readily, also your 'weak spark' thought.
(Might also be worth swapping the HT coil for another if you have one lying around, just to rule that out.)

[g80csp11]

Id recommend as a temporary measure running the ignition system with a separate wiring from the battery , then once proved you can find the fault in the wiring system. very often faults are related to old switches that have high resistance , and voltage drop

[jackstringer]

Today the delivery person brought me some goodies and so I fitted a new battery and a new rectifier.

Turns out you are all wrong, and so was I

It was the damned fuel taps, they were dribbling like Spiddler going for a pee. So gave them a quick reverse blow and there was a little more flow. Took it up the road and woop the thing flies again. Thoughts are that when we opened the throttle they were preventing even the fuel in the carb from flowing as there was a blockage at the tank.

So I will run the fuel down a bit and then see if I have the confidence to remove the old taps to give the filters a clean and the tank a good flushing. That damned Ethanol.

[Groily]

[jackstringer]

Found out that the Cyclone battery was a little low and that may have given me a weak spark. So between the faults it made it hard to work out what had gone wrong.

[SPRIDDLER]

It was the damned fuel taps, they were dribbling like Spriddler going for a pee.

Yebbut, at least I know enough of the basics to have first checked that a pipe wasn't obstructed before assuming it was due to an ear infection or an ingrowing toenail. ........( Cuh! trying to help some people is like feeding strawberries to donkeys ).

[1608]

Thats the problem with filters in the taps/tanks. My new tank isn't a problem, but on the old tanks I simply clean as best as can be expected then remove said filters and rely on the carb banjo filter. Cleaning a blocked tank filter on the road, on a run is no fun.